Nanoindentation and Brillouin light scattering studies of elastic moduli of sodium silicate glasses

Compared to bulk techniques like Brillouin light scattering and ultrasonic measurements, nanoindentation provides a convenient way to investigate the Youngʹs modulus of sodium silicate glasses with reasonably accurate results when Na2O concentration is below 20 mol%. The large discrepancy in the Youngʹs modulus for glasses with higher Na2O contents measured by nanoindentation and the other two bulk techniques is resulted from the pile-up areas created around indents, which was evidenced by 3D AFM images. A structural understanding of the formation of these pile-up areas was gained from Raman spectra of sodium silicate glasses. A simple formula was proposed to correct the Youngʹs modulus of sodium silicate glasses measured by nanoindentation.